IO Wait time signifcance

Team,
What does the IO Wait time indicate. ? Is it the time take for the Data Set to be read over the network ? Does the query wait till the entire Data set is read ?

Thank you

@vrb

Where is your data? Say, it is on HDFS, Dremio will asynchronously send requests to HDFS and in parallel work on other operators, when the time has come to scan data and still the block is not available for read then there is wait time. All data need not be read and can be read in batches. Kindly send the job profile to look further